<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
        ul li:first-child{
            color: red;
        } */
        /* ul li:last-child{
            color: blue;
        } */
        /* ul li:nth-child(5){
            font-size: 30px;
        } */
         /* 偶数 */
        /* ul li:nth-child(2n){
            font-size: 30px;
        } */
        /* 奇数 */
        /* ul li:nth-child(2n+1){
            font-size: 30px;
        } */
        /* 偶数 */
        /* ul li:nth-child(even){
            font-size: 30px;
        } */
        /* ul li:nth-child(5n){
            font-size: 30px;
        } */
        /* ul li:nth-child(n+5){
            font-size: 30px;
        } */
          /* ul li:nth-child(-n+5){
            font-size: 30px;
        } */
        /* 空值 */
        /* div:empty{
          width: 200px;
          height: 200px;
          background-color: pink;  
        } */
        /* ul li:nth-of-type(1){
            color: red;
        } */
        /* ul :nth-child(5){
            color: greenyellow;
        } */
        /* /* ul li:nth-of-type(even){
            font-size: 30px;

        } */
        ul li:nth-child(even){
            font-size: 30px;

        }
    </style>
</head>
<body>
    <div>
        <ul>
            <span>我的天</span>
            <li>123</li>
            <li>123</li>
            <li>123</li>
            <span>123</span>
            <li>123</li>
            <li>123</li>
            <li>123</li>
            <li>123</li>
            <li>123</li>
            <div></div>
        </ul>
    </div>
</body>
</html>